1. Field of the Invention
The present invention relates to a universal joint, and more particularly to a universal joint having a pair of shaft members each having a pair of yoke portions and a ball-like member to be interposed and held between the yoke portions of the shaft members, the shaft members being freely connectable and disconnectable relative to each other via the ball-like member therebetween so that the interconnected shaft members become movable relative to each other across the ball member.
2. Description of the Related Art
A universal joint of the above-noted type is known from e.g. a Japanese published utility model gazette No. 42-14012. In this universal joint, the pair of yoke portions of each shaft member form, in mutually opposing faces thereof, receiving faces together for receiving the ball member therebetween. Further, in each receiving face, there is formed a groove for permiting withdrawal of the ball member by pulling the ball member in a direction substantially normal to the rotational axis of the shaft member holding this ball member. In this way, the shaft members can be freely connected to and disconnected from each other by detaching the interconnecting ball member therebetween.
In the above-described conventional joint, the ball member is detached and attached respectively for disassembly and assembly of the joint, from the direction substantially normal to the axis of either shaft member. More particularly, for attaching the ball member, first, the ball member is inserted between the yoke portions of one shaft member from the direction substantially normal to the rotational axis of this shaft member. Second, the other shaft member is fitted to the ball member held between the yoke portions of the first-mentioned shaft member, from the direction substantially normal to the rotational axis of the other shaft member so that the ball member effects a relative sliding movement, whereby the two shaft members are movably connected with each other via the ball member therebetween.
That is, the joint assembly requires two steps of operations and the above joint consists essentially of three elements: the two identical shaft members and the ball member.
With the above art, the ball member is constructed independently of, i.e. separately from the shaft members. This can cause inconvenience that the ball member can be lost during transportation or assembly. Further, since this type of ball member is usually very small, manual assembly of the same with the shaft members tends to be troublesome.